1. Field of the Invention
The present invention relates to a handover technology that may be applied to a fusion-type Optical Network Terminal (ONT) equipped with a wireless module in a Passive Optical Network (PON)-based system, and more particularly, to a mobility technology for seamlessly supporting data services even when a mobile terminal, such as a notebook computer, a Personal Digital Assistant (PDA), or a smartphone, moves between ONTs.
2. Description of the Related Art
A Passive Optical Network (PON)-based system has a structure in which a single Optical Line Terminal (OLT) controls a plurality of Optical Network Terminals (ONTs), unlike an Ethernet network technology.
Additionally, since the OLT transmits data to all of the ONTs every 125 us, it is advantageous to facilitate broadcasting and multicasting.
However, due to a broadcasting characteristic of the PON-based system, the OLT needs to set a unique number of a specific ONT and to transmit downstream traffic to the specific ONT, so that the specific ONT may receive the downstream traffic. Additionally, to verify a terminal connected to the ONT, the OLT needs to manage a Look-Up Table (LUT) in which a source Media Access Control (MAC) address of the terminal and a unique number of the ONT are mapped. The OLT may update and add the LUT, only when the terminal connected to the ONT transmits data upstream.
For example, when a mobile terminal is included in the PON-based system, the OLT may not instantly update the LUT due to uncertain time in which the mobile terminal transmits upstream data. Accordingly, the mobile terminal may not determine which ONT is connected to the mobile terminal. As a result, the mobile terminal may fail to receive data.
When the mobile terminal performs handover between ONTs, a data service may be interrupted.